1. Field of the Invention
This invention relates to a device for winding up a continuously arriving foil web into a coil on a winding shaft, including a rotatably driveable contact roller for feeding the foil web in a conveying device, as well as the following assigned to the contact roller: a wind-up station for the winding shaft for winding the coil; a take-up station for receiving a fresh winding shaft which is used during a winding shaft change in the winding station, for being exchanged with the winding shaft on which a coil of the foil web has been wound; and a transverse cutting device for transversely cutting the foil web between the winding station and the take-up station, wherein during a winding shaft change the winding shaft supporting the coil can be removed out of the winding station, the transverse cutting device for transversely cutting the foil web can be moved from a position of rest into a working position, and while cutting the foil web a leading end piece of the following foil web is formed, the leading end piece of the foil web thus formed can be conducted to the fresh winding shaft located in the take-up station and can be wound on the fresh winding shaft, and after receiving the leading end piece of the foil web the fresh winding shaft can be transferred from the take-up station into the winding station.
This invention also relates furthermore to a method for winding a continuously arriving foil web into a coil on a winding shaft and to the performance of a winding shaft change for exchanging the winding shaft on which a coil has been wound for a fresh winding shaft, having a winding device with a contact roller, over which the foil web is supplied and is received on a winding shaft rolling off on the contact roller and is wound to form a coil, and having a transverse cutting device for the foil web for cutting the foil web while forming a leading end of the following cut-off foil web for placing it on a fresh winding shaft, as well as a conveying device for conveying in a fresh winding shaft to be exchanged for the winding shaft on which the coil has been wound during a winding shaft change, wherein at the start of the winding shaft change the fresh winding shaft is placed on the contact roller while forming a contact gap, and the foil web is cut either prior to passing through the contact gap or after having passed through the contact gap, and the leading end of the foil web formed while cutting is taken up by the fresh winding shaft.
2. Description of Related Art
Winding devices are distinguished because the continuously arriving foil web is continuously wound into a coil wherein, after a preset coil diameter is reached, the passing on of the coil wound on the winding shaft and the supply of a fresh winding shaft for forming a new coil from the foil web occurs in an automated fashion without it necessary to interrupt the continuous feeding of the foil web. Such winding devices with automatically performed winding shaft changes are known from German Patent Reference DE-AS 15 74 426 and U.S. Pat. No. 3,350,027.
A winding device of the species is described, for example, in German Patent Reference DE 42 13 712 C2, the entire disclosure of which are explicitly included in this specification, by reference.
During a winding shaft change, up to now the leading end piece of the following foil web formed by the transversely cutting device has been usually taken up by the fresh winding shaft, or by a cardboard tube arranged on the fresh winding shaft, in such a way that the circumference of the winding shaft has an adhesive, for example an adhesive strip, to which the leading end piece of the foil web adheres while passing through the take-up station and which is taken up by the fresh winding shaft in the take-up station. Although this method has proven itself in actual use, it cannot always be advantageously performed in connection with all types of foil webs, in particular plastic foil webs, because adhesive residue sticking to the foil web can inevitably have a disadvantageous effect during further processing of the foil web wound into a coil. Also, the application of an adhesive, for example in the form of adhesive strips, is undesirably expensive.
Therefore various attempts have been made to perform the take-up of the leading end piece of the foil web formed during a winding shaft change without the aid of an adhesive, which is called an adhesive-free take-up.
It is known from German Patent Reference DE 36 30 572 C2 to forcibly supply the leading end piece, formed by the transverse cutting device, to the fresh winding shaft by a pressure device, which surrounds the winding shaft over the circumference, having a circulating conveyor belt, and assisted by appropriately directed blast air, so that this leading end piece of the foil web is taken up by the fresh winding shaft. However, it has been shown in actual use that a pressure device with a circulating pressure belt does not make possible satisfactory and dependable take-up of the leading end piece on the fresh winding shaft under all operational conditions and that it fails, in particular above a certain conveying speed of the continuously fed foil web and above a certain thickness of the foil web.
It is one object of this invention to provide a winding device of the type mentioned above but with a dependable and assured take-up of the leading end piece of the foil web formed by the transverse cutting device on the fresh winding shaft, performed even at high conveying speeds and/or large foil thickness of the continuously fed foil web, without it necessary to use an adhesive.
The embodiments of a winding device in accordance with the distinguishing characteristics set forth in the claims and in this specification can be used to achieve this object.
A method of this invention for performing a winding shaft change in the sense of the above described object of this invention is described in the claims and in this specification.
This invention can be employed in connection with a winding device having main components that are known per se, such as described in German Patent Reference DE 42 13 712 C2. In accordance with this invention, the known winding device is modified to attain the stated object in order to make possible desired adhesive-free winding of the leading end piece of the foil web on a fresh winding shaft during a winding shaft change.
In accordance with this invention, in the conveying direction of the foil web, a charging device and a blower device are provided downstream of the take-up station receiving the fresh winding shaft. The leading end piece of the foil web formed by the transverse cutting device can be electrostatically charged by the charging device. A blast air stream can be generated by the blower device, which acts on the end piece of the foil web in the area between the contact roller and the end piece of the foil web.
Therefore the winding device in accordance with this invention makes use of an electrostatic charge of the leading end piece of the foil web for receiving the leading end piece of the foil web on the fresh winding shaft, by which the leading end of the foil web automatically adheres to the circumference of the fresh winding shaft and is taken up by the latter, so that the continuous winding of the foil web proceeds without interruption. Adhesive is no longer required. To aid the placement of the leading, electrostatically charged end of the foil web on the circumference of the fresh winding shaft, the blast air is directed toward the circumference of the fresh winding shaft and on the side of the foil web facing away from the fresh winding shaft, so that the electrostatically charged leading end of the foil web is guided toward the fresh winding shaft and adheres to the winding shaft because of the electrostatic charge.
A field of electrical tension is formed between the foil web and the winding shaft by the charging device. A winding shaft according to this invention is also considered to be a winding shaft with a winding tube pushed on it, for example a cardboard tube.
The method of this invention, for performing a winding shaft change in the winding device for the foil web, particularly those made of plastic, is distinguished because the leading end piece of the foil web is electrostatically charged and is deflected toward the circumference of the fresh winding shaft by blast air.
The charging device can preferably be formed by a charging electrode extending transversely over the entire width of the foil web. Such charging electrodes are commercially available for various applications.
Different charging methods are basically available here. For one, it is possible to connect the charging electrode with a direct current (d.c.) voltage source, while the remaining parts of the winding device of this invention are grounded, therefore also the winding shaft. Because of the electrostatic field generated, the foil web will temporarily adhere to the reference ground, in the present case to the circumference of the winding shaft because of the deflection by blast air.
It is also possible to connect the charging device to a d.c. voltage source and to let the foil web pass between the charging electrode and an a.c. voltage ion spray device, by which it is also possible to achieve the desired electrostatic charge of the foil web.
To produce a sufficient adherence of the leading end piece of the foil web at the circumference of the fresh winding shaft, the discharging device is advantageously charged with an electrical potential of up to 40 kV.
The blower device of the winding device of this invention advantageously comprises a plurality of blast jets arranged over the entire width of the foil web, which are evenly charged with compressed air from an appropriate compressed air source. Because of the charging electrode extending over the entire width of the foil web, and because of the multitude of blast jets arranged over the entire width of the foil web, which advantageously also are at equal distances from each other, the leading end piece of the foil web is evenly placed against the circumference of the fresh winding shaft and is taken up by the fresh winding shaft.
Also, the blower device and/or the discharging device can be arranged on a pivotable holder and, in case of a winding shaft change, can be moved from a position of rest into a working position and, following the end of the winding shaft change, back again into the position of rest, so that they are in the working position only for the length of the winding shaft change, but in the remaining time are assigned to a protected position of rest, in which they do not hinder the further functioning of the winding device.
In another embodiment of the winding device of this invention, the contact roller is perforated in the area of its circumference and the blower device is arranged inside the contact roller and has at least one blast air conduit with a blower jet, which is conducted to a circumferential area of the contact roller which, viewed in the conveying direction of the foil web, is located downstream of the take-up station. Blast air can be generated from the blast air conduit through the perforated circumference of the contact roller, in the direction toward the circumference of the fresh winding shaft. With a blower device embodied this way, it is possible to effectively assist removal of the foil web from the contact roller and its placement on the fresh winding shaft rolling off on it. It is also possible to put the blower device together from both of the above mentioned variations, for example with a plurality of blower jets arranged over the entire width of the foil web, as well as a blast air conduit embodied inside the contact roller, which directs blast air on the foil web through the perforated circumference of the contact roller.
Also, it is possible to activate the charging device and the blower device only during the time of the winding shaft change with an appropriate control, but to deactivate it during the remaining operating time of the winding device of this invention, because during that time the operation of the charging device and of the blower device are not required. This activation as needed of the charging and blower devices can be integrated without problems into the running control of the winding device in accordance with this invention.
This invention can be advantageously employed in the described manner in connection with a winding device in accordance with German Patent Reference DE 42 13 712 C2, wherein the contact roller is selectively driven in different directions, so that the foil web is wound up into a coil of the desired orientation.
A method in accordance with this invention, for executing a winding shaft change in connection with a winding device of this invention, for performing a winding shaft change, has the transverse cutting device moved into a position between the take-up station and the winding station. The fresh winding shaft is brought into the take-up station by the conveying device, wherein the fresh winding shaft is put into a rotating movement on the contact roller prior to being deposited in the take-up station. The charging device is switched on as soon as the fresh winding shaft rests on the contact roller while forming a contact gap, wherein the electrostatic charge is provided by an electrical voltage drop between the foil web and the fresh winding shaft. Then the transverse cutting device is activated and the foil web is cut by the transverse cutter. The blower device is activated simultaneously with the transverse cutting of the foil web and an air flow is generated, wherein the new leading end piece of the following foil web formed in the transverse cutting device is lifted by the air flow and is conducted against the fresh winding shaft by the static charge and is wound up. Also, the winding shaft in the winding station, on which the coil is wound, is removed from the winding station. Thereafter, the fresh winding shaft with the taken-up end piece of the foil web is transferred from the take-up station to the winding station for winding a new coil.
It is obvious that the winding device of this invention and the method of this invention, which relate to a charging device and a blower device for placing the leading end piece of the foil web on the circumference of the fresh winding shaft without the use of adhesives, can also be retrofitted with little cost outlay in already installed winding devices. It is thus only necessary to arrange a suitable blower device and appropriate charging device in a suitable manner and position them on the winding device already installed in an installation for producing and winding foils and to integrate it into the running control. Thus, the take-up free of adhesives which is possible with this invention can be retrofitted with little cost outlay in already existing winding devices of various designs.